Painless injection device

ABSTRACT

AN INJECTING DEVICE FOR A HYPODERMIC SYRINGE RAPIDLY PROJECTS THE SYRINGE NEEDLE THROUGH A SURFACE ENGAGING END OF A HOUSING ADAPTED TO FIT WITHIN THE HAND. AN INJECTOR BAR ACTUATES THE SYRINGE PLUNGER AFTER THE NEEDLE HAS PENETRATED THE SKIN AND TISSUES. PRIOR DISENTIZING OF THE SKIN BY DISCHARGE OF COOLANT FROM A PRESSURIZED CONTAINER IN THE HOUSING, MAY BE UTILIZED TO REDUCE PAIN AND IRRITATION. THE NEEDLE PROJECTING MECHANISM MAY ALSO BE CONDITIONED TO PRODUCE ASPIRATION FOR DETECTING WHETHER THE NEEDLE HAS PENETRATED A BLOOD VESSEL, BEFORE MEDICATION IS INJECTED BY THE PLUNGER.

Sept. 20, 1971 R. c. Tl-BBS PAINLESS INJECTION DEVICE 3 Sheets-Sheet 1 Filed Feb. 3, 1970 Robert C. Tibbs 3 Sheets-Sheet 2 Filed Feb. 5, 1970 Fig 2 3 Robert C. Tibbs INVIiN'I'OK.

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Sept. 20, 1971 R. c. TIBBS PAINLESS INJECTION DEVICE 3 Sheets-Sheet 5 Filed Feb. 5, 1970 Robert C. Tibbs ted States Patent 3,605,742 PAINLESS INJECTION DEVICE Robert C. Tibbs, Cleveland, Miss., assignor of fractional part interest to Eugene E. Tibbs, Cleveland, Miss. Filed Feb. 3, 1970, Ser. No. 8,366 Int. Cl. A61m /20 U.S. Cl. 128-218F 14 Claims ABSTRACT OF THE DISCLOSURE An injecting device for a hypodermic syringe rapidly projects the syringe needle through a surface engaging end of a housing adapted to fit within the hand. An injector bar actuates the syringe plunger after the needle has penetrated the skin and tissues. Prior desensitizing of the skin by discharge of coolant from a pressurized container in the housing, may be utilized to reduce pain and irritation. The needle projecting mechanism may also be conditioned to produce aspiration for detecting whether the needle has penetrated a blood vessel, before medication is injected by the plunger.

This invention relates to hypodermic injection of fluids through the needle of a plunger operated syringe and more particularly to a new and useful injecting device for hypodermic syringes minimizing pain, discomfort and psychological trauma commonly associated with hypodermic injections.

The present invention pertains to a mechanical device adapted to removably receive a conventional type of hypodermic syringe in order to enable a medical technician or physician to inject fluids into the subcutaneous and muscular tissues under the skin of a patient in accordance with a more desirable injection method. Thus, the injection device of the present invention embodies various desirable injection techniques which prior art devices were incapable of incorporating in one instrument.

In accordance with the present invention, a conventional hypodermic syringe is inserted through an access opening in an elongated housing with the barrel of the syringe being received within a slidable holder for projecting the syringe needle by spring operated means through a surface engaging end of the housing. A releasable latch mechanism retains the cocked holder in a retracted position with the hypodermic needle completely enclosed within the housing. Upon release of the latch mechanism, the holder and the needle is rapidly advanced to a limit position. The releasable latch mechanism may be also provided with a brake element that engages an injector bar coupled to the plunger of the syringe so as to resist movement thereof and thereby produce a negative pressure within the barrel of the syringe as the barrel holder is rapidly advanced by the spring operated mechanism. As a result of this aspiration effect, if the needle penetrates any blood vessel, blood will be withdrawn into the barrel of the syringe and may be viewed through a window in the door closing the access opening through which the syringe is inserted into the housing. After the needle has penetrated the skin without drawing blood, the injector bar may be depressed in order to actuate the syringe plunger and thereby discharge the contents of the syringe barrel.

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Prior to releasing of the syringe barrel holder from its retracted position, the skin in contact with the surface engaging end of the housing may be desensitized by discharge of a coolant from a pressurized container also enclosed within the housing in a separate chamber. A finger operated lever mounted on the housing may therefore be manipulated in order to displace a pressure release valve so that coolant discharged from the container may be directed through a passage in the housing onto the skin surface in contact with the surface engaging end of the housing through which the hypodermic needle is projected.

These together with other objects advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIG. 1 is a perspective view showing the injecting device of the present invention.

FIG. 2 is a longitudinal sectional view taken substantially through a plane indicated by section line '22 in FIG. 1.

FIG. 3 is a side sectional view taken substantially through a plane indicated by section line 3-3 in FIG. 2.

FIG. 4 is a side sectional view taken substantially through a plane indicated by section line 44 in FIG. 2.

FIG. 5 is a bottom plan view of the injecting device shown in FIG. 1.

FIG. 6 is a transverse sectional view taken substantially through a plane indicated by section line 66 in FIG. 1.

FIG. 7 is a transverse sectional view taken substantially through a plane indicated by section line 77 in FIG. 1.

FIG. 8 is an enlarged partial sectional view taken substantially through a plane indicated by section line 88 in FIG. 6.

FIG. 9 is a partial sectional view showing the valve release mechanism illustrated in FIG. 4 in an actuated position.

FIG. 10 is an enlarged partial sectional view of a portion of the device illustrated in FIG. 2 showing the pressure release valve in an actuated position.

FIG. 11 is a perspective view of some of the disassembled parts associated with the injecting device.

FIGS. 12, 13 and 14 are partial side sectional views similar to FIG. 3 but showing the injecting device in different operational phases.

Referring now to the drawings in detail and initially to FIG. 1, the hypodermic injecting device generally denoted by reference numeral 10 includes an elongated support housing or case generally referred to by reference numeral 12. Although various shapes are contemplated, the housing as illustrated in the disclosed embodiment is rectangular in cross-section having parallel spaced front and rear walls 14 and 16 interconnected by side walls 18 and 20. The housing is closed at one longitudinal end by an end wall 22 as more clearly seen in FIGS. 2 and 5. This end wall is adapted to be placed against the skin surface of a patient. An end wall 24 closes the opposite longitudinal end of the housing. The front wall 14 is provided with an access opening 26 removably closed by a closure or door member 28. Hinges 30 pivotally mount the door on the side wall 18 of the housing. The door may open or close by means of a handle formation 32 positioned just below a thumb rest formation 34. The thumb rest formation confronts a yieldable door latch enclosure 36 mounted on the front wall 14 adjacent to the access opening 26. The door member 28 is thereby yieldably held in the closed position shown in FIG. 1. A viewing window 38 is mounted in the door member adjacent one longitudinal end for purposes to be explained hereinafter. An elongated opening or slot 40 is formed in the side wall 18 of the housing intermediate the longitudinal ends thereof in order to accommodate a finger projection 42 associated with a spring-operated mechanism to be described hereinafter. In one embodiment of the invention, the housing 12 also pivotally mounts, between pivot brackets 44, a finger actuating lever 46. The lever 46 is formed with a finger contact portion 48 at one end aligned with the thumb rest 34 on the door member 28. The lever extends into the housing through an opening 50 formed in the front wall 14 adjacent the end wall 22. The end wall 24 is provided with an opening 52 through which an injector bar 54 slidably projects. Also, a closure cap 56 is threadedly mounted in the end Wall 24 adjacent to the opening 52 for purposes to be explained hereinafter.

As more clearly seen in FIGS. 6 and 7, the housing is provided with a partition wall 58 to internally divide the housing into a syringe chamber 60 and a coolant chamber 62 in one form of the invention as illustrated. The side Wall 18 and partition wall 58 are provided with flanges 64 and 66 as shown in FIG. 7 against which the door member 28 abuts in the closed position illustrated. Thus, only the syringe chamber 60 is exposed by opening of the door member 28.

Referring now to FIGS. 2, 3, 6, 7 and 11, the syringe chamber 60 Within the housing slidably mounts a spring operating mechanism generally referred to by reference numeral 68. The spring operating mechanism includes an elongated holder 70 having a U-shaped cross-section forming a cavity 72 with an internal groove 74 adjacent one longitudinal end 76 for slidably receiving the end flange portion 78 of a syringe barrel 80 forming a part of a conventional type of hypodermic syringe generally referred to by reference numeral 82. The finger projection 42 extends from the end 76 of the holder 70' through the opening 40 in the side wall 18 of the housing as hereinbefore indicated. The cross-sectional shape of the holder 70 is such as to accommodate with sliding clearance, its movement within the chamber 60 of the housing parallel to the longitudinal axis of the housing. Thus, the finger projection 42 will be at one end of the elongated opening or slot 40 in the side wall 18 of the housing when the holder 70 is in a retracted position as illustrated in FIGS. 1, 2 and 3.

Also associated with the spring operating mechanism 68, are a pair of spring members 84 that extend through lateral slots 86 formed in the sides of the holder. The spring members 84 are anchored at one of their axial ends to the holder adjacent to the groove 74 by pins 88 as more clearly seen in FIG. 2. The opposite ends of the spring members 84 are anchored to the housing by pins 90 disposed adjacent to the end wall portion 22 of the housing.

Received within the chamber 60 of the housing abutting the end wall portion 22, is a stroke limiting member 92 having a central slot 94 aligned with the cavity 72 in the holder 70 so that the hypodermic needle 96 mounted on the barrel 80 of the syringe may be projected, from a position completely retracted within the housing, through the outwardly diverging aperture 98 formed in the end wall 22. In order to cushion the impact of the holder 70 when it reaches the end of its stroke, a thrust absorbing Washer 100 is disposed between the stroke limiting member 92 and the end wall 22 within the syringe chamber 60 while the end of the holder 70 opposite the end 76 is provided with a cushioning surface 102. It will therefore be apparent that when the holder 70 is released from its retracted position as shown in FIGS. 2 and 3, the springs 84 i will rapidly advance it into engagement with the stroke limiting member 92 the thickness of which is selected in order to regulate the depth to which the needle 96 is projected. The spring members 84 extend through lateral slots 104 formed in the stroke limiting member so as to be anchored by the pins 90 in the end wall 22 of the housing.

It will be apparent that both the holder 70 and the stroke limiting member 92 are received within the syringe chamber 60 through the access opening 26 in the front wall 14 of the housing. One corner edge of the stroke limiting member is provided with a recess 106 as more clearly seen in FIG. 11 adapted to receive an internal projection 108 at one end of the partition wall 58 in order to accurately seat the stroke limiting member 92 in alignment with the slidably mounted holder 70. The stroke limiting member when properly seated may be releasably secured to the housing by means of a screw fastener 110 extending through the side Wall 18 of the housing and adapted to be threadedly received in an internally threaded aperture 112 formed in the stroke limiting member. With the holder 70 and stroke limiting member disposed within the chamber 60 of the housing, the syringe 82 may be inserted by sliding the barrel flange 78 into the groove 74 of the holder. When the door member 28 is then closed, an internal syringe positioning projection 114 thereon will maintain the syringe barrel in proper position as more clearly seen in FIGS. 3 and 7.

Formed on the holder 70 on the back wall opposite the opening of the cavity 72, and adjacent the end 76, are a plurality of spaced ratchet grooves 116 as shown in FIG. 3. In the retracted position of the holder, as shown in FIG. 3, one of the ratchet grooves is aligned with an opening 118 in the back wall 16 of the housing through which a holding pawl formation 120 projects from a latch lever 122 pivotally mounted by a pin 124 intermediate its ends. The pin is mounted on the outside of the housing by a pair of spaced finger rest formations 126 that project from the back wall 16 of the housing. A lever spring element 128 biases the latch lever 122 to a position with its holding pawl formation 120 projecting into the opening 118 so as to engage the syringe holder 70 within one of its ratchet grooves 116 as shown in FIG. 3. The holder 70 is thereby releasably held in the retracted position wherein the spring members 84 are under tension. The holder is cocked when manually displaced to the retracted position by means of the finger projection 42.

The injector bar 54 is generally rectangular in cross section so as to be constrained for slidable movement within the syringe chamber 60 and projects from the end wall 24 as aforementioned. Elastically extensible springs 130 which are weaker than the spring members 84, are anchored at oneof their ends by pins 132 to the injector bar 54 adjacent the projecting end 134 thereof while the opposite ends of the springs 130 are anchored by pins 136 to a generally rectangular coupler element 138. The springs 130 thus extend through lateral grooves 140 formed in opposite sides of the injector bar. The coupler element 138 on the other hand is provided with a T- shaped slot 142 adapted to slidably receive the flanged end portion 144 of the syringe plunger 146 that slidably extends from the syringe barrel 80. Thus, the coupler element 138 and springs 130 operatively couple the injector bar to the syringe plunger for purposes to be hereinafter explained.

The injector bar-54 is provided on one side with a serrated groove 148 that extends longitudinally from the end 150 which is adapted to abut the coupler element 138. The serrated groove 148 is aligned with an opening 152 in the back wall 16 of the housing through which a brake element 154 is adapted to project. The element 154 is mounted on the end portion of the latch lever 122 opposite the pawl formation 120 so that when the latch lever is depressed against the bias of the spring 128 to release the pawl formation from the holder 70, the element 154 will be engaged in the groove 148 on the injector bar to prevent the same from moving. Thus, release of the syringe holder 70 will permit the spring members 84 to advance the holder and the syringe in order to project the hypodermic needle 96 but the injector bar 54 will be prevented from being advanced therewith. However, the syringe plunger 146 and the coupler elernent 138 will advance somewhat against the bias of springs 130 while the injector bar is held stationary as shown in FIG. 12 causing the springs 130 to become extended since they are substantially weaker than the spring members 84 causing advancement of the syringe holder 70. When the latch lever 122 is released, as shown in FIG. 13, the springs 130 displace the injector bar 54 inwardly into abutment with the coupler element 138. The injector bar is then in condition for operating the syringe plunger in order to discharge the contents of the syringe barrel through the hypodermic needle 96. A slot 156 is formed in the coupler element in order to avoid interference with the holding pawl formation 120 on the latch lever which projects into the housing through the opening 118 as shown in FIG. 14. When the injector bar 54 is displaced to the position shown in FIG. 13, another serrated groove 158 formed thereon adjacent to one of the slots 140 becomes aligned with a spring detent 160 mounted through an opening in the side wall 18 of the housing adjacent the end wall 24 as more clearly seen in FIG. 8. Thus, the injector bar will be stabilized by the detent element '160 with a relatively small holding force.

The threaded closure cap 56 mounted in the end wall 24 of the housing, provides access through the end wall for replacement of a pressurized container 162 held within the coolant chamber 62 of the housing. The fluid contents of the container 162 may be a highly volatile coolant liquid such as a fluorinated or chlorinated hydrocarbon. The discharge end 164 of the container is seated on a conical formation 166 as more clearly seen in FIGS. 2 and 4 and is provided with a pressure release valve cap 168 of a conventional type commonly associated with pressurized fluid dispensers. The pressure release valve cap is provided with a nozzle passage 170 as more clearly seen in FIG. through which the pressurized contents of the container is discharged in a predetermined direction when the valve cap 168 is pressed inwardly. The valve cap 168 is adapted to be displaced inwardly for this purpose by means of an actuating lever element 172 having a slotted arm portion 174 as more clearly seen in FIG. 4 engaged by a pin at the end of the finger lever 46 which projects through the opening 50 into the housing. Thus, when the finger lever is displaced against the bias of the spring 176 from the position shown in FIG. 4 to the position shown in FIG. 9, the liquid coolant from the container will be discharged into the passage 176 which communicates with the aperture 98 in the end wall 22. Thus, by depressing the finger contact portion 48 of the lever 46, the operator may discharge a selected quantity of coolant onto the surface with which the end wall 22 of the injector device is in contact.

The injector device 10 is loaded through the access door member 28 with the hypodermic syringe 82 containing a desired medication, and the spring operating mechanism 68 is cooked by displacement of the finger projection 42 to the upper end of the opening 40. The housing 12 is conveniently held in position in one hand of the operator with the thumb resting on the thumb-rest formation 34 and the fingers engaging the back wall 16 spaced from the lower end portion of the latch lever 122 by the finger-rests 126. The surface engaging wall 22 of the housing is then placed on the skin of the patient at a desired location. Since the hypodermic needle will be completely enclosed within the housing, psychological trauma sometimes induced in children, is thereby eliminated. By sliding the thumb over the portion 48 of the finger lever 46 a selected quantity of coolant may be discharged onto the portion of the skin to be penetrated by the hypodermic needle thereby desensitizing this portion of the skin in order to reduce pain by producing partial anesthesia, in view of the rapid and extreme lowering in temperature of the skin. This also acts as a counter irritant. After the skin has been desensitized, the upper finger may depress the latch lever 122 to release the pawl formation thereby effecting rapid displacement of the holder 70 and penetration of the skin by the hypodermic needle to a depth regulated by the stroke limiting member 92. The rapid introduction of the needle into the tissues also diminishes the amount of pain produced. As hereinbefore indicated, the injector bar 54 is initially held against movement by the brake element 154 on the latch release lever so that the springs may resist movement of the syringe plunger 146 while the remainder of the syringe assembly is advanced with the holder 70 to develop a negative pressure within the syringe barrel. However, due to the fact that the needlepoint is spaced closely adjacent the plane of the end wall 22 which rests upon the skin area overlying the tissue through which the needle will be advanced, see FIG. 2, the needle point enters the skin and underlying tissue before any such negative pressure can develop, thus eliminating any possibility of drawing air into the needle prior to discharge of the contents of the syringe barrel therethrough. After the needle has entered the tissue upon which the end wall 22 rests, the negative pressure will be formed as expansion of the springs 130, which were previously slack or untensioned, occurs during continued movement of the holder 70 toward the member 92. This causes inflow of blood into the lower portion of the syringe barrel through the needle 96 should the needle penetrate any vein. The operator may detect the presence of blood within the syringe barrel by viewing it through the window 38. If no vein or blood vessel has been penetrated, then the operator may inject the contents of the syringe barrel into the tissues after the injection bar is released by depressing it.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

What is claimed as new is as follows:

1. In combination with a syringe having a barrel, a needle and a plunger, an injection device comprising an elongated housing having an end surface through which the needle is adapted to be projected, a holder slidably mounted in the housing and supporting the barrel of the syringe therefrom with the needle end adjacent said end surface, spring means operatively connected to the holder for movement of the same thereby projecting the needle through said end surface of the housing, said housing and holder including releasable coacting latch means for bolding the holder in a retracted position wherein the needle is completely enclosed within the housing, an injection bar slidably mounted in the housing and projecting therefrom, means operatively coupling the injection bar to the plunger for operatively positioning the injection bar relative to the holder, limit means limiting said movement of the holder upon release of the holder by the latch means for regulating penetration of the needle, said coupling means including a coupler element engaged with the plunger, elastically extensible means connecting the coupler element to the injection bar and holding means mounted by the latch means engageable with the injection bar in response to said release of the holder to effect relative displacement between the barrel and plunger of the syringe against the bias of said elastically extensible means during projection of said holder to the limit position thereof defined by said limit means under the biasing action of said spring means.

2. The combination of claim 1 including detent means yieldably retarding displacement of the injection bar after its engagement with the coupler element following release of the holding means.

3. The combination of claim 2 including selectively actuated desensitizing means mounted by the housing for discharging a fluid into a zone in contact with said end surface of the housing.

4. The combination of claim 3 wherein said desensitizing means includes a container of coolant having a pressure release valve, lever means mounted on the housing for displacement of the valve to discharge said fluid from the container, and passage means mounted in the housing establishing fluid communication between the valve and said end surface of the housing.

5. The combination of claim 1 including selectively actuated desensitizing means mounted by the housing for discharging a fluid into a zone in contact with said end surface of the housing.

6. The combination of claim 5 wherein said desensitizing means includes a container of coolant having a pressure release valve, lever means mounted on the housing for displacement of the valve to discharge said fluid from the container, and passage means mounted in the housing establishing fluid communication between the valve and said end surface of the housing.

7. The combination of claim 5 wherein said coupling means includes a coupler element receiving the plunger in spaced relation to the holder, elastically extensible means connecting the coupler element to the injection bar and holding means mounted by the latch means for engagement with the injection bar in response to said release of the holder to effect relative displacement between the barrel and plunger of the syringe against the bias of said elastically extensible means.

8. In combination with a syringe having a barrel, a plunger and a needle mounted on the barrel, an injection device comprising a housing having a surface engaging end having an opening formed therethrou-gh, said barrel being supported from said housing for reciprocation to retract and project said needle through said opening, spring operated means engageable with the barrel for projecting the needle from a retracted position within the housing, latch means mounted on the housing and engageable with the spring operated means for releasably holding the needle in said retracted position, means engageable by the spring operated mean for limiting movement of the needle to an extended position, actuating means rendered operative in the extended position of the needle for displacing the plunger relative to the barrel thereby discharging fluid through the needle, a syringe plunger holder supported from the housing for reciprocation relative to the latter and shiftable relative thereto with said barrel and means connected between said housing and said holder for retarding movement of the plunger holder, and thus said plunger, during movement of said barrel in a direction to project said needle to develop a negative pressure within the barrel.

9. The combination of claim 8 including selectively actuated desensitizing means mounted by the housing for discharging a fluid into a zone coextensive with the portions of said housing end defining said opening.

10. The combination of claim 9 wherein said desensitizing means includes a container of coolant having a pressure release valve, lever means mounted on the housing for displacement of the valve to discharge said fluid from the container, and passage means mounted in the housing establishing fluid communication between the valve and said end surface of the housing.

11. In combination with a syringe having a barrel, a plunger and a needle mounted on the barrel, an injection device comprising a housing having a surface engaging end having an opening formed therethrough, said barrel being supported from said housing for reciprocation to retract and project said needle through said opening,

spring operated means engageable with the barrel for projecting the needle from a retracted position within the housing, latch means mounted on the housing and engageable with the spring operated means for releasably holding the needle in said retracted position, means engageable by the spring operated mean for limiting movement of the needle to an extended position, actuating means rendered operative in the extended position of the needle for displacing the plunger relative to the barrel thereby discharging fluid through the needle, and aspiration means for resisting movement of the plunger to develop a negative pressure within the barrel during movement of said barrel by the spring operated means, selectively actuated desensitizing means mounted by the housing for discharging a fiuid into a zone coextensive with the portions of said housing end defining said opening, said desensitizing means including a container of coolant having a pressure release valve, lever means mounted on the housing for displacement of the valve to discharge said fluid from the container, and passage means in the housing establishing fluid communication between the valve and said end surface of the housing, said housing further including an internal partition forming a syringe chamber and a coolant chamber, an opening in the housing providing access to the syringe chamber a removable closure for the last mentioned opening, and a thumb rest formed on the closure, said lever means having a finger surface portion aligned with the thumb rest externally of the housing.

12. In combination, a syringe having a barrel, a needle and a plunger, an injection device comprising an elongated housing having an end surface thereof with an opening formed therethrough through which the needle is adapted to be projected, a holder slidably mounted in the housing and supporting the barrel of the syringe therefrom with the needle end adjacent said end surface, spring means operatively connected to the holder for movement of the same thereby projecting the needle through said end surface of the housing, releasable latch means mounted on the housing and engageable with the holder for holding the same in a retracted position where in the needle is completely enclosed within the housing, means limiting said movement of the holder upon release of the holder by the latch means for regulating penetration of the needle, and selectively actuated desensitizing means mounted by the housing for discharging a fluid substantially throughout a generally planar zone coextensive with and bound by the portions of said end surface defining the periphery of said opening, said desensitizing means including a container of coolant having a pressure release valve, lever means mounted on the housing for displacement of the valve to discharge said fluid from the container, and passage means in the housing establishing fluid communication between the valve and said opening in said end surface of the housing, said housing including an internal partition forming a syringe chamber and a coolant chamber, an opening in the housing providing access to the syringe chamber, a closure for the last mentioned opening, and a thumb rest formed on the closure, said lever means having a finger surface portion aligned with the thumb rest externally of the housing.

13. In combination with a syringe having a barrel, a plunger and a needle mounted on the barrel, a support, a syringe barrel holder from which said barrel is supported mounted on said support for reciprocal shifting along a predetermined path relative to said support for projecting and retracting, respectively, the needle carried by said syringe barrel mounted on said holder, a syringe plunger holder, from which said plunger is supported, mounted on said support for reciprocal shifting along said path rela tive to said support and shiftable relative thereto with said barrel holder, and means connected between said support and said syringe plunger holder operative for re tarding movement of said plunger holder, and thus said plunger, during movement of said barrel holder and barrel in one direction along said path in order to develop a negative pressure within the barrel.

14. The combination of claim 13 wherein said support includes surface means disposed about a target zone centrally through which the free end of a needle supported from a hypodermic barrel carried by said barrel holder is likewise advanced during movement of said barrel holder along said path in said one direction, and fluid discharge means carried by said support and operable to discharge fluid toward said zone from a discharge point spaced in the opposite direction from said zone.

References Cited UNITED STATES PATENTS 2,671,448 3/1954 Harnisch 128-218F 2,960,087 11/1960 Uytenbogaart 128-2l8F 2,867,214 1/1959 Wilson 128355 FOREIGN PATENTS 143,084 5/1920 Great Britain 1282l8F 202,961 7/1956 Australia 128-218F CHANNING L. PACE, Primary Examiner 

